Hydrogen is the energy vector of the future, and many developments are in progress in the domain of fuel cells, hydrogen combustion engines and related technologies. However, the economic and ecological costs of the manufacturing, transport and the storage of hydrogen are the obstacles to a rapid change of an economy based on fossil fuels toward an economy based on hydrogen. Hydrogen production by thermal dissociation of water in a membrane reactor, in the waning stage by using solar energy, is not only neutral for the environment, but it may also provide a potentially high efficiency.